This invention relates to a two-cycle engine and more particularly to an improved cooling and lubricating system for such engines.
As is well known, lubricant is supplied to an engine for not only its lubrication but also for cooling purposes. With two-cycle engines this presents some difficulties. A conventional .method of lubricating two-cycle engines has required the operator to mix lubricant with the fuel that is consumed by the engine. There are, however, a number of difficulties with such arrangements, particularly in emission control and the desire to maintain a more accurate control over the amount of lubricant supplied to the engine to serve all of its running conditions. When lubricant must be mixed with the fuel, the fuel lubricant ratio must contain enough lubricant to adequately lubricate the engine under the most severe running conditions and this provides excess lubricant under most running conditions.
It has, therefore, been proposed to provide so-called "separate lubricating systems" for two-cycle engines wherein the lubricant is supplied to the engine in a manner other than mixing it with the fuel. For example, the system may be provided with an arrangement wherein lubricant is sprayed into the inducted air or is pumped directly to certain components of the engine for their lubrication. Although these systems may be satisfactory for most components, there are some instances wherein a more positive control of the lubricant supply and cooling for certain components of the engine is provided.
For example, although the big end of the connecting rod can be well lubricated by spraying lubricant into the intake charge, the small or piston pin end of the connecting rod may not receive adequate lubricant for cooling and lubrication under this method. The reason for this is that the piston pin and small end of the connecting rod are concealed within the piston and there may not be adequate air flow through this area for either cooling or lubrication.
If the big end of the connecting rod is supplied with lubricant by a pressure feed system through the crankshaft, then it is possible to drill the connecting rod with a passage that will extend up to the piston pin end for lubrication and cooling purposes. However, this method is rather expensive to employ in that it requires additional machining of the connecting rods and also may not ensure adequate cooling of the small end of the connecting rod.
It is, therefore, a principal object to this invention to provide an improved apparatus for cooling and lubricating a two-cycle crankcase compression internal combustion engine.
It is a further object of this invention to provide an improved apparatus for cooling and lubricating the small or piston pin end of a connecting rod of such engines.